Why would I use a low angle smoother?

[James Taglienti]

Low angle jack and smoothers seem pretty popular, so they must work well. What acts as a chipbreaker? Arent they basically just a single iron plane? I have heard a few explanations, such as "the blade acts as the chipbreaker" , "the mouth is so tight it doesnt need a chipbreaker" , and "this configuration doesn't need a chipbreaker." I don't know if I believe either one! If I have a low angle plane with a bed/iron that is equal to 50* and a bevel down plane with a blade set at 50* AND a chipbreaker, wouldn't it be a no brainer?
So i guess my question is, If low angle planes work so well, and they do seem something to rave about, is the chipbreaker then just a vestigial piece of junk? I have some standard angle planes without chipbreakers and they seem more prone to tearout.
I very rarely make NEW tool purchases but LV bevel up smoother looks soo sweet and you guys seem to really love it. But I work some figured woods and I don't want to buy this plane and then regret it either.

[David Keller NC]

Chris Schwarz wrote a series of blog entries on "how to prevent tearout" - I think they were on the Woodworking Mag blog, but might be on the Lost Art Press Blog. His conclusion about chipbreakers were that they were completely ineffective unless their edge was within a few thousandths of the cutting edge of the iron. Most planes, even high quality new ones from LV/LN, don't make a setting like this easy - when you tighten the cap iron screw, it tends to move the chipbreaker around.

One of the other conclusions was that while blade sharpness and the tightness of the mouth yielded observable effects on tear-out, the biggest factor by far was the angle at which the handplane was presented to the grain and the cutting angle.

That said, it's been my experience that you can get equivalent performance out of a BD as a BU by simply making a quick little jig out of a few scraps of wood to put a consistently repeatable back bevel on the blade.

[Rob Fisher]

...back bevel on the blade...

Wouldn't a back bevel change the effective cutting angle of the plane? Increasing it by whatever the degree of the back bevel is? And while this is a perfectly acceptable way to increase the planes effectiveness it's not comparing apples to apples...or angles to angles as it were.

Rob

[Dave Beauchesne]

James:

I have a BU smoother and it is indeed sweet.

The fact it can be configured ( with a different grind or blade ) from low angle to higher angle was the selling point for me; it works well at both.

The geometry of the blade naturally peels the shavings away, something like a chipbreaker, however, and this is just MHO, I think the chipbreaker was more than its name implies ( to some degree anyway ).

While it helps with chip ejection, it also stabilizes the '' flimsy '' blade, reducing chatter on the frog. If you had a nice thick blade in a BU ( with a bit different engineering of course ) the chipbreaker would not be necessary.

Don't get me wrong, I have a # 4, type 11 with original laminated blade that I really enjoy using; it can, with one pass, make a piece of rosewood shimmer. While the debate goes on, there are the pros and cons to both, again, due to the fact the BU can be double threat with the change of a blade and not fiddling around with a HA frog, steep back bevels etc. is what sold me.

JMHO

Dave Beauchesne

[Tri Hoang]

Here are why I use a BU smoother (among a few BD smoothers):

1. Adjustable mouth - handy for fine adjustment and especially clean out
2. Fast/simple blade removal/install - no chip breaker to mess with when sharpening is required
3. Easy to adjust blade angle to combat tear out - BD blades can have back bevels too but I hate to flatten it up again

Things that I don't like

1. Center of gravity - not feel quite as comfortable as a BD (at least on my LV BU smoother)
2. Putting on a camber - a little more complicated than a BD blade because what you see (with a straight edge) isn't what you got (with the shavings)

[Chris Friesen]

There are a few things going on here:

1) It's really easy to use a high cutting angle on a bevel up plane--this is great for figured wood. Yes, the cutting angle can be increased on a bevel-down plane by using a back bevel. This is absolutely apples-to-apples as compared to a bevel-up with the same cutting angle. However, I suspect it's a bit more work because you really need to work both sides of the iron rather than just polishing the back.

2) Yes, a bevel up plane is a single iron plane. However, on a bevel-up plane, the iron is supported by the body of the plane right out almost to the cutting edge. On a bevel-down plane the whole length of the bevel is unsupported. I have a theory that the cap iron basically pretensions this area of the blade so it doesn't chatter.

3) The center of gravity of the LV BUS is lower than a bevel-down plane. This gives it a different feel.

4) The clearance angle of a low-angle plane is smaller. Some people think this makes them more sensitive to slightly dull irons.

[Paul Murphy]

Jim, I have wondered about the chipbreaker also. I don’t really know the answer, but have a couple observations. The low angle planes bed the blade pretty much all the way to the end of the sole, while bevel down planes offer sometimes less support due to frog positioning. The mass market bevel down plane often was designed around a fairly thin blade, and I wonder if the chipbreaker added necessary rigidity to the thin blade. As I understand it, the actual “chip” is formed at the microscopic area in front of the blade, so it would seem to me that to truly be effective in breaking chips, the end of the chipbreaker would have to be as close as possible to the tip of the blade. The bedding angle of the bevel down plane also subjects the blade to a force vector much more directly in line with any likely deflection concern. My speculation is the chipbreaker “pre stresses” the blade to this deflection value, and further acts to stabilize the blade against chatter.

I have read that bevel up planes experience somewhat more of a wear bevel to the flat side of the blade due to reduced clearance angle. The bevel down plane has the greater clearance angle, and the wear bevel would seem to be more directly addressed with sharpening. It seems to me that the bevel up plane might need more metal removed during sharpening to fully remove the wear bevel.

OK, that was a lot of speculation!:eek:

I think two things are “self evident”:
One, if a chipbreaker wasn’t “necessary” to a bevel down metal plane it would have been phased out for profit reasons.
Two, the LV bevel up smoother indeed works well without a chipbreaker.

If you want the LV bevel up smoother, you aren’t taking a huge risk. The BUS has been out for a while, it has been well received, and you could always resell it if you find it doesn’t suit you.

[Joel Goodman]

The chipbreaker or cap iron has another function in a Stanley type plane -- it gives a place for the adjuster pawl to connect to. The nice feature of this design is whether the iron is long or short, within reason, the plane adjuster will work. I suspect that this function, along with stabilizing the edge of the thin iron are the main functions of the "chipbreaker". Neither C&W nor Gordon nor Breese planes use one and all work well.

[Sam Takeuchi]

The original patent (posted here nearly a year ago I believe) by Bailey for cap iron/blade and frog assembly stated the use of cap iron enable use of thin blade. I believe the function or the idea of 'chip breaking' is a bi-product and after thought, that it was not envisioned for such function originally.

While there may have been planes with cap irons even before Bailey's design, cap iron/blade assembly is quite recent addition to the bench plane genealogy, probably going back only about 150 years as standard design and sporadic appearances in other planes prior to that. Everything else before were pretty much single blade planes.

As I said, the main function is to stiffen the thin blade. This "chip breaking" and what not, it's not the primary function of this piece of metal. Also for metal planes, it engages lateral and depth adjusters.

I'm on in the other camp. If blade is thick and adjustment function is engaged without cap iron, why would you want one whether it's for BU or BD? I rather think of cap iron as necessary evil for thin blade. I'd do it away if I could.

[James Taglienti]

I like the blade support thing. THat sounds nice. THe blade switching thing sounds good too.
The chipbreaker predates Stanley by a long long time. There are many wooden planes with huge tapered irons and chipbreakers. So I don't think it was designed per se to pretension a blade. These 1/4" thick irons arent going to flex. It has GOT to do something!
I think I am going to have to rig a Bailey type plane with no chipbreaker, or take the chipbreaker off one of my other smoothers, to get a good gauge.
I'll report back.

[jerry nazard]

There is an interesting thread on the chipbreaker currently running on woodnet. (MODS: Is it OK to mention another forum if you do not link to it? Please delete this if it violates SMC rules. Thanks, Jerry)

[lowell holmes]

Steve Knight has already done it on his woodies. Bevel down, 1/4" iron, . . . .no chatter. Have you tried a Knight smoother, you should.:)

I have three of his planes.

[James Taglienti]

Thanks guys!